In this step, we will create a StorageClass for Portworx volumes.

Step: Understand StorageClass

A StorageClass provides a way for administrators to describe the “classes” of storage on their Kubernetes cluster. Before we create a volume in Kubernetes, we have to create a StorageClass.

For example, the following is a Portworx StorageClass whose volumes have replication factor of 3 and high IO priority.

• Replication factor of 3 means the data for the volume is replicated on 3 different nodes in the cluster
• High IO priority means Portworx will use storage devices that are classified into the high IO profile (for e.g SSDs).

kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
    name: px-repl3-sc
provisioner: kubernetes.io/portworx-volume
parameters:
   repl: "3"
   priority_io: "high"

Step: Create StorageClass

Let's create the above storage class.

kubectl create -f px-repl3-sc.yaml

Let's proceed to creating volumes that use this storage class.

In this step, we will deploy a PersistentVolumeClaim using Portworx.

Step: Understand PersistentVolumeClaim

A PersistentVolumeClaim can be used to dynamically create a volume using Portworx.

For example, below is the spec for a 2GB volume that uses the Portworx Storage class we created before this step.

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
   name: px-pvc
   annotations:
     volume.beta.kubernetes.io/storage-class: px-repl3-sc
spec:
   accessModes:
     - ReadWriteOnce
   resources:
     requests:
       storage: 2Gi

Step: Create PersistentVolumeClaim

Let's create the above PersistentVolumeClaim.

kubectl create -f px-pvc.yaml

Behind the scenes, Kubernetes talks to the Portworx native driver to create this PVC. Each PVC has a unique one-one mapping to a PersistentVolume which is the actual volume backing the PVC.

Step: Validate PersistentVolumeClaim

A PersistentVolumeClaim is successfully provisioned once it gets into "Bound" state. Let's run the below script to check that.

echo "Checking if the PersistentVolumeClaim was created successfully..."

while true; do
    PVC_STATUS=`kubectl get pvc px-pvc | grep -v NAME | awk '{print $2}'`
    if [ "${PVC_STATUS}" == "Bound" ]; then
        echo "px-pvc is ${PVC_STATUS} !"
        kubectl get pvc px-pvc
        break
    else
        echo "Waiting for px-pvc to be Bound..."
    fi
    sleep 2
done

Let's proceed to the next step to further inspect the volume.

In this step, we will use pxctl to inspect the volume

Step: Inspect the Portworx volume

Portworx ships with a pxctl command line that can be used to manage Portworx.

Below we will use pxctl to inspect the underlying volume for our PVC.

VOL=`kubectl get pvc | grep px-pvc | awk '{print $3}'`
PX_POD=$(kubectl get pods -l name=portworx -n kube-system -o jsonpath='{.items[0].metadata.name}')
kubectl exec -it $PX_POD -n kube-system -- /opt/pwx/bin/pxctl volume inspect ${VOL}

Make the following observations in the inspect output

• HA shows the number of configured replcas for this volume
• Labels show the name of the PVC for this volume
• Replica sets on nodes shows the px nodes on which volume is replicated
• State indicates the volume is detached which means no applications are using the volume yet